The number 420 became cannabis slang in California in the early 1970s and later spread worldwide as a symbol of weed culture, with April 20 and 4:20 pm treated as smoking references. Blaze it added a direct call to light up, and the combined phrase circulated in forums, image macros and MLG montage parodies in the 2010s. Its drawn out meme delivery keeps it useful as shorthand for ironic stoner humor long after the original montage era faded from mainstream feeds.